Round the World Racers Unveil New Sailing Speed Tracker

The 2011-12 edition of the triennial Volvo Ocean Race, a nine-month, around-the-world yacht showdown, officially began on October 29th with an in-port challenge in Alicante, Spain. Tomorrow the six competing ships will set sail for the first of nine major legs of the competition, a 6,500-mile trek from Alicante to Cape Town. Aiming to improve on its second place finish in the 2008-09 Ocean Race, the crew of Newport, Rhode Island-based Puma Ocean Racing spent the past year and a half developing groundbreaking nautical technology and doubling down on its approach to fitness. In the first of two reports, we break down a new way to track a boat’s speed in the water.

The Doppler Velocity Logger, or DVL, is the black circle on the keel bulb of Puma's boat.

Until this summer, the crew of the Puma yacht Mar Mostro measured its boat speed the same way every other craft in the Volvo Ocean Race still does: poorly. With no engine to tap for output data, crews have had to rely on a paddle wheel, an underwater device that yields approximate velocity through the water based on the force of the water flow. The technology is rudimentary, and the results it produces are accordingly unreliable. Since speed information is vital to accurately navigate and adjust to weather conditions, it’s understandable that teams wanted a more precise alternative. As it revealed this week, Puma Ocean Racing has one: the Doppler Velocity Log, a sonar-based system that effectively slaps a precision speedometer on their figurative dashboard.

It’s almost incomprehensible that in a sport with as many big money practitioners as yacht racing, something as critical as a trustworthy speed gauge remained elusive for so long. “The paddle wheel did produce a boat speed, but it wasn’t precise,” explains DVL project manager Robert Hopkins. “Readings were affected by the distorted flow of water as it came off the boat’s submerged appendages, and at times part of the boat is out of the water and the speed doesn’t register at all. We came away with a lot of bad data.”

The paddle wheel also couldn’t help measure leeway, or the sideways force acting on a boat as it moves forward. The Volvo Open 70 class of yacht has a system of underwater daggerboards and keels that allow for compensation against unintended drift, but to maximize efficiency a crew needs to know how much adjustment is needed. “When there’s not a lot of side force motion, we can reduce drag by pulling out appendages,” says Puma skipper Ken Read. “But there was never a way to properly determine that.” During the Ocean Race’s ten sprint-like in-port competitions, fine tweaks don’t have much impact. But when sailing 6,500 miles, an accumulation of small gains can translate into crucial wins.

Puma partnered with Norwegian-based oceanographic lab Nortek to create the new instrument. After eighteen months of development and four prototypes, they came away with the DVL, a sleek, circular device embedded in the keel bulb meters beneath the boat. It emits four beams, one in each direction, that bounce off matter in the water—Nortek designed it to reflect off plankton—and, based on positional change, accurately depict the path and rate of the boat’s movement.

The tech made its debut during this summer’s Rhode Island-to-southern England Transatlantic Race, which the Puma team won. Skipper Read is quick to point out that the DVL was just “one of a thousand factors” that contributed to the crew’s victory, but nevertheless acknowledges the advantage granted by the previously top-secret device. With an exclusivity deal that prohibits Nortek from selling the technology to another Volvo team for the duration of this Ocean Race, the crew can sail assured that their edge will be preserved throughout. “We’ve only been using the DVL since this summer, and already I can’t imagine not having it,” says Hopkins. “Now we can completely trust our data. Other teams have to question theirs.” With nine months of sailing ahead, they’ll have plenty of time to do so.

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